MRI & X-RAYof the Neonate Spine

by Lynn Davis

1895 - Wilhelm Röntgen begins investigating the effects of electron beam emissions, and accidentally discovers the “shadow” image of his wife’s hand on a paper plate coated in barium platinocyanide.

1895 - 1897 - Röntgen publishes three papers discussing x-rays as a new type of medical imaging.

1901 - Röntgen receives the Nobel Prize for Physics for his discovery and research on x-rays.

A BRIEF HISTORY OF X-RAY

(Nobel Lectures, 2012)

HOW DOES X-RAY WORK?

X-rays consist of electromagnetic waves, which are similar to light waves only more energetic. This means they are able to penetrate more materials.

A cathode emitter produces the beams, which penetrate the subject to varying degrees and on to a film that is behind the subject.

Various tissues absorb the rays differently, causing a different level of exposure to the film.

Bone does not allow much of the beam to transmit, therefore the bone on an x-ray is white. Lung allows for most of the beam to be transmitted through, causing it to be a darker gray shade.

(McCoy)

(Harris)

HISTORY OF MRI1970 - Raymond Damadian demonstrated differences in cancerous tissue from rats with NMR (nuclear magnetic resonance) imaging, the early name for MRI.

1973 - Paul Lauterbaur imaged the first living object with MRI, a small clam.

1972 - Damadian applies for patent on his concept of MRI, which he received in 1974.

1977 - With the help of graduate students, Damadian constructs an MRI machine. It contained approximately 30 miles of niobium-titanium wire, and had a liquid helium cooling system mounted on the top. An imperfect system, the helium leaked miserably and ended up costing the team about $2,000/week. This early MRI was called Indomitable.

1980 - The Fonar Corporation marketed a prototype based on the Indomitable.

1982 - Fonar drops Damadian’s complicated MRI concept in favor of Lauterbaur’s simpler version and continues production of MRI machines, which started making their way into hospitals.

(Wakefield, 2000)

(Ainali, 2012)

Winding 30 miles of niobium-titanium wire on two spools.

One of two liquid helium cooling units.Raymond Damadian (left), Larry Minkoff (middle) and Michael

Goldsmith (right) posing with Indomitable in 1977.

All images: (Wakefield, 2000)

HOW DOES MRI WORK?

(Kalapurayil, 2009)

A strong magnetic field is created by passing an electric current through metal loops.

Coils in the magnet start to send and receive radio waves.

Protons in the body begin to align themselves, and once this occurs the radio waves are absorbed by those protons. Then they begin to spin.

The energy that is released from these spinning protons emits an energy signal which varies based on the type of tissue they reside in.

The signals are received by magnetic coils and sent to a computer for processing.

The processing computer then produces a “voxel” image by interpreting the radio waves received, which is what we end up seeing in an MRI image.

http://www.youtube.com/watch?v=H5q79R9C-mk

BASIC ANATOMY33 total vertebral bodies:

7 cervical vertebrae (C1-C7)

12 thoracic vertebrae (T1-T12)

5 lumbar vertebrae (L1-L5)

5 fused sacral vertebrae (S1-S5)

4 fused coccygeal vertebrae (tailbone)

Intervertebral disks

("Houston orthopedic and," 2009)

(Hagen-Ansert, 2012)

BASIC ANATOMY OF THE SPINAL CANAL

• Spinal Cord• Body of the cord• Conus Medullaris (caudal end of cord)• Cauda equina (bundle of nerve roots

inferior to conus)• Filum terminale (tapering end of the

cord where the pia mater layer extends into the sacrum and terminates the cord)

(Cunningham, 1903)

(Hagen-Ansert, 2012)

• Cerebrospinal fluid

SPINAL PATHOLOGY

(Fitzgerald, 2011)

WHAT IS NORMAL?

(Chandiran, 2011)

(Fitzgerald, 2011)

On the MRI, conus is centrally located in canal at L1.

On the US, the conus is centrally located at L2.

Both are normal.

Text

L1

L2

L3

L4

L5

S1

T12

TETHERED CORD

(Howe, Johanek & Moore, 2007)

A tethered cord is the adhesion of the spinal cord to surrounding tissue, preventing free motion and growth.

MRI to left shows a tethered cord with a low-lying conus at L4/L5 disk space, with a clear posterior adhesion.

US shows a tethered cord with low-lying conus at L5 (left arrow) as well as a thickened echogenic filum (right arrow).

X-ray would be used to determine if there are any bony abnormalities causing the low lying conus such as 11 rib sets.

(Gaillard, 2008)

S1

L5

L4

L3

LIPOMA

(Howe, Johanek & Moore, 2007)

A spinal lipoma consists of focal fatty tissue that can displace the spinal cord, causing tethering.

MRI to left shows a hyperintense mass posterior to the spinal cord cauda equina with no apparent

subcutaenous involvement.

US below shows hyperechoic mass posterior to the cauda equina.

(Birmingham Children's Hospital, 2004)

DORSAL DERMAL SINUS

(Schenk, 2005)

A dorsal dermal sinus is the failure of skin closure that leaves an open path through the spine. It may or may not extend all the way to the spinal canal,

and it is very prone to infection.

The MRI shows a small hypointense tract starting at the cutaneous layer extending all the way to the

spinal canal.

US below shows a hypoechoic canal extending from the spinal canal to the superficial layers.

(Schenk, 2005)

DIASTOMYELIA

Diastomyelia is a split/duplication of the spinal cord within the canal.

Both MRI and US show an axial view of a split spinal cord.

(Birmingham Children's Hospital, 2011)

(Fitzgerald, 2011)

INDICATIONS

Infants that may have a spinal ultrasound may have the following:

sacral dimple

palpable subcutaneous mass

tuft of hair

skin tag

hemangioma

sinus tract

skin pigmentation spots (“port wine stain”)

infants with multiple congenital abnormalities

(Thompson, 2010)(Thompson, 2010)

PATIENT PREP

✤ NPO for sedation, if needed

✤ Administration of contrast

✤ Ear plugs/MRI-safe headphones

✤ All metal objects removed (patient and guardian)

✤ MRI-safe incubator/immobilizer (if needed)

✤ No prep needed for X-ray

(Troyka Med, 2012) (Wilking, 2010)

(Fitzgerald, 2011)

MRI V. ULTRASOUND V. X-RAY

MRIAdvantages:

• Extreme detail resolution

• No ionizing radiation

• No patient repositioning

• May show abnormalities that are not able to be seen with US/Xray because of bony structures

Disadvantages:

• Long scan times

• Sedation with some younger children

• Loud noises that might scare young patients

• Cost

•Inherent dangers of very strong magnets

(Jones, 2012)

UltrasoundAdvantages:

• Non-invasive

• No ionizing radiation

• Dynamic imaging

• Portable

• Low cost

Disadvantages:

• Operator dependent

• Inability to view spinal structures of older infants due to ossification

• Inability to safely visualize with open skin lesions due to infection

(Fitzgerald, 2011)

X-rayAdvantages:

• Non-invasive

• Painless

• Excellent visualization of bony structures

• Fast exam

Disadvantages:

• Ionizing radiation risk, particularly for pediatrics

• Potential reaction to contrast agents

("U.s. food and," 2012)

HOW DO THESE MODALITIES COMPLIMENT EACH OTHER?

Physicians often start with an ultrasound when an anomaly is discovered in

neonates, since there is no radiation, contrast or sedation needed for an exam.

If there are abnormal findings on the ultrasound or if the infant spine has

ossified, an X-ray for bony abnormalities may be ordered or an MRI for internal

severity exploration.

Combining all imaging modalities to aid in diagnosis benefits the patient and

gives the doctor “the big picture.” (United Medical Instruments, 2010)

QUESTIONS?

Ainali, J. (Photographer). (2012). Mri. [Web Graphic]. Retrieved from http://www.thefeeherytheory.com/2010/06/29/mri/

Birmingham Children's Hospital. (Photographer). (2004).Intradural spinal lipoma. [Web Photo].

Birmingham Children's Hospital. (Photographer). (2011).Diastematomyelia. [Print Photo].

Chandiran, B. (Photographer). (2011). Tethered cord syndrome. [Web Photo].

Cunningham, D.J. Textbook of Anatomy (New York, NY: William Wood and Co., 1903)

Desktop Wallpaper HD. (Artist). (2010). Xray family. [Web Graphic]. Retrieved from http://www.desktopwallpaperhd.com/wallpapers/X-Ray-Family-117852.html

Fitzgerald, K. (2011). Ultrasound examination of the neonate spine. Autralasian Journal of Ultrasound in Medicine, 14(1), 39-41. Retrieved from http://www.minnisjournals.com.au/ajum/article/Ultrasound-examination-of-the-neonatal-spine-24

Gaillard, F. (Photographer). (2008). Diastematomyelia and tethered cord. [Print Photo]. Retrieved from http://radiopaedia.org/images/3742

Hagen-Ansert, S. L. (2012). Textbook of diagnostic sonography. (7th ed., Vol. 2). St. Louis, Missouri: Elsevier Mosby.

Harris, T. (n.d.). How stuff works. Retrieved from http://science.howstuffworks.com/x-ray.htm

Houston orthopedic and spine institute. (2009). Retrieved from http://houstonorthopedics.org/anatomy-spine.html

Howe, L. H., Johanek, A. J., & Moore, C. W. (2007). Sonography of the neonatal spine: Part 2, spinal disorders. American Journal of Roentgenology, 188(3), 739-744. doi: 10.2214/AJR.05.2160

Jones, J. (2012). Mri. Retrieved from http://radiopaedia.org/articles/mri

Kalapurayil, M. (2009, April 16). Medical news today. Retrieved from http://www.medicalnewstoday.com/articles/146309.php

Mayo clinic. (2012, Oct 24). Retrieved from http://www.mayoclinic.com/health/sacral-dimple/DS00753

McCoy, G. (Artist). (n.d.). Just as i thought, you have bones.. [Web Drawing]. Retrieved from http://www.cartoonstock.com/ cartoonview.asp?start=2&search=main&catref=ggm070813&MA_Artist=Not Selected&MA_Category=Not Selected&ANDkeyword=xray&ORkeyword=&TITLEkeyword=&NEGATIVEkeyword=

Nobel Lectures. (2012, October 18). Nobelprize.org. Retrieved from http://www.nobelprize.org/nobel_prizes/physics/laureates/1901/ rontgen-bio.html

REFERENCES

Schenk, J. P. (Photographer). (2005). Imaging of congenital anomalies and variations of the caudal spine and back in neonates and small infants. [Print Photo].

Thompson, D. (2010). Spinal dysraphic anomalies; classification, presentation and management.Pediatrics and Child HEalth, 20(9), 397-403. Retrieved from http://www.sciencedirect.com/science/article/pii/S1751722210000740

Troyka Med. (Photographer). (2012). Mr compatible baby incubator. [Print Photo]. Retrieved from http://www.troykamed.com/products.php?product=MR- Uyumlu-Bebek-Küvözü-%2d-Nomag

United Medical Instruments. (Designer). (2010).Neonatal/pediatric ultrasound. [Web Graphic]. Retrieved from http://ultrasoundvirtualdemo.com/ultrasound-specialties/general-imaging/pediatric

U.s. food and drug administration. (2012, May 14). Retrieved from http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/ MedicalImaging/ucm298899.htm

Wakefield, J. (2000, June). Smithsonian magazine. Retrieved from http://www.smithsonianmag.com/science-nature

Wilking, R. (Photographer). (2010). Retrieved from http://rickwilking.photoshelter.com/image/I0000kBfRpsxreGc object_jun00.html?c=y&page=1

REFERENCES